you are using self.bannerIsVisible but I can't see neither a synthesize for this nor setters and getters. Did you made a property with bannerIsVisible in your .h file?

To resolve this crash you should define the property in you header and add a @synthesize statement in your implementation.

Maybe you should start with something more basic to get to know the fundamental things like properties, synthesizers, compiler warnings (there should be one), debugging, and so on.
I don't want to be rude, but you won't learn much by using copied code you don't understand.

if the property is there you should add @synthesize bannerIsVisible; below @implementation Vampire_Quiz_FinalViewController. The compiler should give you a warning because this is missing.
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Matthias BauchNov 6 '10 at 10:19